Protective device for electrically-operated mining machines and the like



July 24, 1928.

2* W 5 L! V) 5 I u i t s gwwntoz (IE P111072 Patented J uly 24, 1928.

UNITED STATES PATENT. or

'JAME S E. DILLON, OF MASON'IOWN, FENNSYLVANIA.

, revazss F EQE'.

PROTECTIVE DEVICE FOR ELECTBIOALLY-OPERATED '1VIl lllIN(3r 'MACH-TINES AND THE Y LIKE. i 1 n f Application filed I ebruary 12, 1927. Serial No. 167,803.

This invention relates to protective devices for electrically operated mining machines and the like which are not permanently connected with the negative side of a grounded circuit.

An important object of the invention is the provision of a control for these machines, such that upon break down or failure of the insulation on wires, armatures, coils, controller, rheostat or cablereel, the circuit to the motor is broken and cannot berestored except by a manual operation which,

provided the break down has not been repaired, will be inoperative.

A further object of the invention is to provide a control system of this character which includes means whereby the cable reel upon which the feed cables, by means of which such machines are supplied, are wound, is at all times, during operation of the machine or during idle periods when the machine is still connected with the supplycurrent, grounded, so that in event of a break down of the insulation of the feed' Wire wound thereon, the circuit is broken by blowing of the fuse of the positive feed wire.

A still further object of the invention is to produce a control of this character which embodies means automatically interrupting the circuit in event the feed wires are improperly connected with either the source of supply or the machine.

These and other objects I attain by the construction shown in the accompanying drawing, wherein the figure is a diagram illustrating a control constructed in accordance with myinvention and its connections to the machine. i

Referring now more particularly to the drawing, the numeral 10 generally designates the usual cable reel, upon which positive and negative feed wires 11 and 12 supplying the machine are wound. 13 designates the motor and 14 the metallic frame ofthe machine. The circuit of the motor M is interrupted between stationary contacts 15 and 16 andcoacting movable contacts 17 and 18 carried by the armature 19 of a main control coil 20. The circuit is, of course, likewise interrupted by placement of the controller arm 21 of a rheostat R in the off position.

The contacts 15 and 16 are directly connected with the positive and negative feed wires by wires 22 and 23 which are concontacts are connected to the negative wire 23 and to one terminal of the coil :20 respectively. The contact 27 is also connected to one contact 28 of a pair of contacts 28 and 29 with which the contacts 17 and 18 engage when the coil .20. is de-energiz ed.

The contact 29 is electrically connected to the'frame of the cable reel by' a/wire 30. The negative wire 23 includesthecoil 31 of a series relay, the armatureof which coacts with the contacts '32 and 33 which areconnected to. the wire 30 and; wire 23 respectively. When themotor circuit is closed, the circuit between the contacts 32 and is closed connecting the negative wire: 23 to the reel frame.

The controller arm 21 supports an insulated contact element 34, which, when the controller arm is coacting with; any. of the contacts of the rheostat, electrically co nnects pair of contacts 35 and 36. The contact 35 is connected to the positive wire 22, while the contact 36 is connected with'one contact 37 of a pair of contacts 37 and 38.

The contact 38 is connected to the second terminal of the coil 20. The contacts 37 a'nd 38 form a portion of the ground relay, the coil 39 of which is connected to thelmotor circuit between the contact 18 and the motor .13 andis connected to theframe 14 of the machine.

The insulated support associated with the with the contacts 28 and 29, The armature of the coil 25, when energized, provided the g currentis properly fed to the machine, closes upon the contacts 26 and 27 electrically connecting the. same."

11 and 12 are properly connectedand are properly connected tothe wires 22 and '23 and the, controller arm "21 is in the off position, the contacts 17 and'28 and 18and' v The operation is as follows If the leads contacts 26, 27, 28 and 17, the controller arm, contacts 18,29 and w-ire30 with the reel frame, so that if there exists any break down of insulation, causing grounding of the positive wire 22 at the reel, a blow-out of the fuse of the positive feed wire 11 will occur. to the on position, the contact 34 connects thecontacts35 and36, with the result thata circuit is'established from the positive wire 22 through the contacts 35', 3.4: and 36, contacts37 and 38, coil 20, contacts 27 and 26 to'the negative feed wire. The coil 20 being energized, the armature 19 is attracted connecting the contacts 15 and 1.6 to the contacts 17 and" 18' and completing the-motor circuit.

It will be noted that the. circuit of the motor is controlled through. the ground relay and in event at theltime the motor circuit is established there is a break down of insulation, permitting positive cur-rent to flow to the frame 14: of'the machine, a circuit will be established from. this frame through the coil 39, contacts 18 and 16 to the negative wire 23; This will attract the armature of the ground relay, breaking the circuit of the coil 20 between the contacts 37 and 38, thereby causing the. armature 19 to: move to open position where its contacts 17 and 18 engage the contacts 28 and 29. The armature 13 of. the ground circuit relay includes anextension 14' in the form of a rack bar, coacting with a pawl i5, which serves to retain the armature in its open circuit position until it is moved to the closed circuit. position by a manual op.- eration. I f'this manual operation is effected and the break has not been repaired,.,a secondattempt to move the controlarm 21 to its 'on position will. have the same result. It will be noted that at all times when the motor circuit is complete, the armature of the coil 31' has closed upon the contacts 32 and 33', connecting the reel frame in the negative circuit to replace. the connection broken by the movement of the armature 19. 7

1 Since the control mechanism hereinbefore described is capable of a certain range of change and modification without. materially departing from the spirit of. the invention, I. do not limit myself to such specificstructure except as hereinafter claimed;

1. In a safety system for. electrical motor operated machines the frames of which are not, permanently connected to the negative side-of a grounded circuit, a normally open circuit for the motor including a rheostat, positive and negative feed wires for the motor. circuit, a reel upon which the feed wires are wound, a control circuit including When the controller arm' is moved" means for closing the motor circuit operative'only when the rheostat controller arm is in on position, parallel connections between thenegativeside of the motor circuit and the reel frame, one of which is nominally open and the other of which is nominally closed, said means when the motor circuit is open closing the open con.- nectionand means opening the other of the connections when the motor circuit is closed.

2. In a. safety system for electrical motor operated machines the frames of which are not permanently connected to the negative side of a grounded circuit, a normally'open circuit for the motor including arheostat, positive and negative feed wires for the motor circuit, areel upon whicht'he feed wires are wound, a: control circuit; including an electro-magnet switch for closing the motor circuit operative only when the rheostat." controller arm is in on" position, parallel connections between the negative side of the motor circuit and-thereel frame, one of which is normally open and" the other of which is normally closed, said switch having a baclrcontact which when the motor circuit is open closes the open connection and a series relay in the negative side of the motor circuit for opening theother of the connections.

3; In a safety system for electrical motor operated machines the frames'of which are not permanently connectedito' the negative side of a. grounded circuit, anormally open circuit for the motor including a .rheostat, a control circuit 'includingmeans for closing the motor circuit operativeonly when therheostat controller arm is in on. position, means foropeningthe control. circuit j if the frame of the machine is positively charged and manually releasable means for retaining the last named means .in open circuit position and means for rendering said circuits inoperative upon a reversal of the feed connections to the machine.

41-. In av safety system for electrical motor operated machines the frames of which are not permanently connected tothe negative side of a grounded circuit, a normally open circuit for the motor including. a rheostat, a' control circuit including means for closing the motor circuit operative only when the rheostat. controller arm is in on position, means for opening the control circuit if the .frame of the machine is positively charged, manually releasable means for retaining the last named. means in open. circuit position and a reverse current relay rendering all of said circuits inoperative upon a reversal of the feed connections to the machine. j

In testimony whereofl hereunto allixmy signature.

JAMES E. DILLON. 

